Motorola Corporation

William B Beckwith

Joseph Staudinger

Warren L Seely

John M Golio

Jean B Verdier

Warren P Reif

A power amplifier (50) includes two transistors (11, 21) and a dynamic biasing circuit (52). The dynamic biasing circuit (52) uses a sampling circuit (54) to generate a bias adjusting signal proportional to the amplitude of an AC signal at a drain electrode of the first transistor (11). The bias adjusting signal is combined with a constant voltage bias signal to generate a dynamic biasing signal applied to a gate electrode of the second transistor (21). As the gain of the first transistor (11) decreases, the amplitude of the AC signal at its drain electrode decreases. Thus, the dynamic biasing circuit (52) generates a lower dynamic biasing signal at the gate electrode of the second transistor (21), thereby decreasing a quiescent drain current in the second transistor (21) and improving the efficiency of the amplifier (50) at low output power levels.

Method for dynamically biasing an amplifier and circuit therefor

A communication device (104) includes a radio frequency power amplifier (202) and a bias circuit (204). The power amplifier (202) includes a depletion mode MESFET (214) for RF power amplification. To properly bias the MESFET (214) in a circuit including logic components powered by a conventional battery (136), the bias circuit (204) includes a level shifter (223) to provide the necessary gate-to-source voltage for the MESFET (214). To maintain the RF output power from the communication device (104) constant over temperature, the bias circuit (204) output voltage varies over temperature to track the temperature variation of the MESFET (214).

Voltage bias and temperature compensation circuit for radio frequency

An attenuator circuit uses single point control to adjust the attenuation levels between first and second nodes. The attenuator is set-up as a .pi.-network with a pass transistor and first and second shunt transistors. Capacitors are coupled in the drain and source conduction paths of the first and second shunt transistors for DC isolation to float the shunt transistors. A control voltage applied at the drain of the pass transistor and the gates of the first and second shunt transistors controls the attenuation level. A parallel resistor and capacitor combination at the drain of the first shunt transistor provides tuning to match the input impedance of the attenuator to the sourcing circuit.

Attenuator circuit operating with single point control

A signal mixing apparatus comprising first and second four port signal splitting/combining networks having no relative phase shift between three ports and 180.degree. of phase shift between the remaining ports, coupled to a four port mixer element. The mixer element has two ports coupled to the first signal splitter/combiner network and having another two ports coupled to the second splitter/combiner, RF and LO signals input to the first splitter/combiner do not appear at the IF output from the second splitter/combiner or vice versa. The RF/IF signals cancel and the LO signal is trapped by a resonant circuit within the mixer. The RF and IF frequency bands may overlap.

Broadband mixer circuit and method

A method and apparatus for improved isolation of IF, LO, and RF frequency signals from the non-associated mixer ports (e.g., avoiding introducing RF frequency signals at the IF and LO ports, and similarly vis-a-vis other signals and ports), is provided by coupling a RF (or LO) signal to first ports of four-port first and second phase shift means, each having two signal output ports having 180.degree. phase difference for signals input from the first port, coupling the LO (or RF) signal to the first port of a third phase shift means, with two output signal ports having a phase difference of 180.degree., supplying the third phase shift means output signals to fourth ports of the first and second phase shift means, supplying the output signals of the first and second phase shift means to distinct ports of a five port mixer, and coupling an IF signal from the five port mixer to an IF port.

High isolation mixer

A N-stage differential distributed amplifier arrangement. The differential distributed amplifier arrangement includes a parallel connection of N-differential amplifiers. The inputs to the amplifiers are delayed so that the same input is received by each amplifier in sequence at a slightly later time than the preceding amplifier. The outputs of each amplifier are also delayed so that the output of the previous amplifier is added to the output of the next sequential amplifier. Thereby the output is an amplified version of the input. By appropriate grounding of inputs or outputs the differential distributed amplifier arrangement may convert from balanced signals to single-ended signals, from single-ended signals to balanced signals or from two inputs to two outputs.

Distributed differential amplifier arrangement

A method for creating a four-port quadrature coupler suitable for monolithic implementation which involves connecting two ports of a balun, suitable itself for implementation in monolithic microwave integrated circuits, to two separate phasing networks. A device exhibiting the proper four-port quadrature coupler characteristics within a MMIC structure results, with wide bandwidth exceeding one octave.

Four-post quadrature coupler suitable for monolithic implementation

Overlapping gate electrodes are selectively energized to vary the electrical length and thus the resistance of the conductive path through a field effect attenuator. The electrical width can also be varied to provide additional control over the resistance.

Field effect attenuator devices having controlled electrical lengths

A miniature wide-band microwave power divider comprising a common terminal connected to a plurality of parallel signal paths with each signal path comprising a low pass and a high pass filter made up of discrete components. Use of discrete components allows the entire power divider to be incorporated on a single chip. Isolation is achieved between the signal paths by isolation means comprising resistors.

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Chandler, AZ, United States of America

William B Beckwith